Improvement in instruments for describing ellipses



UNITED STATES PATENT OFFICE.

J. B. ATWATER, OF CHICAGO, ILLINOIS.

Specification forming part of Letters Patent No. 38,720, dated June 2, 1863.

To all whom t may concern:

Be it known that I, J. B. ATWATER, of the city of Chicago and State of Illinois, have invented certain new and useful Improvements in Apparatus for Describing Ellipses, Circles, and other Figures; and I hereby declare that the following is a true and exact description of the same, reference. being had to the accompanying drawings, and to the letters of reference marked thereon.

Figurel in the drawings, which are made a part of this specification, represents a vertical section of my machine when in position. Fig. 2 is a section of the shaft with the scale marked on it. Fig. 3 is a section of the slide with the ellipses attached to it.

The letter A represents the shaft, which is made square from the point where it rests on the base B to the circular shoulder which supports the movable clamp C. The clamp or guide C is formed with a circular hole through it, and is iitted on the neck of the shaft A, above the shoulder, the neck being made cir-- cular to receive it. The top or handle of my machine, marked d, consists of a circular head and shoulder with a pin extending from the center of the shoulder. This pin,whic`h is an inch (more or less) in length, fits tightly in a hole made in the upper end of the shaft A. When the clamp or guide is placed in position on the neck of A, the top d is put-in place by forcing the pin at the end of it into the hole in A, and pressed down until the shoulder on d rests on the upper edge of the clamp C. The clamp C is made sufficiently long to allow of a mortise or opening at the outward end of it to admit of the insertion of the rod E. The rod E is made square at top, where it is inserted in the opening in C, and then made rounding to the end, which reaches nearly as low down as the base of A. The rod E has a metal ferrule on the lower end, with a hole in its center extending some three inches upward. This hole is intended to receive apen or pencil. At the upper end of the hole is adjusted the spiral wire spring .I/,the object of which is to given suiiicient pressure on the pen or pencil to enable it tol perform its office. The upper end of the rod E works on a pivot which passes through it and through the jaws of the clamp or guide C, by which its motion is adapted to the ellipscs or other gure to be described.

Between the jaws of C, and resting on the shoulder formed by them, is inserted the curved spring f,the concave side of which rests against vthe said shoulder and the convex against the inner side of the rod E. This spring extends an inch (more or less) below the jaws of C, and its object is to press the rod E against the edge of the ellipsis F.

G is a slide, with a square mortise extend-4 ing longitudinally through it, in which the shaft A is inserted, and embraces the shaft A loosely enough to admit of its being raised or depressed at pleasure. The upper part of the slide is adjusted and secured at any desired point by a small screw passing through one side of it, the end of the' screw resting against A. The lower end of the slide G consists of a wheel which may be turned solid with G and slightly beveled at the circumference, so that when the ellipsis F, which has a hole through it of corresponding size, is slipped upward it embraces this wheel so closely as to retain its position. B designates the base of the shaft A, which is made circular and less in diameter than the opening in F, so that F can easily pass over it when it isremoved to substitute another gure in its place. The bottom of B is formed with a plane surface, and has several metallic points in it to penetrate the paper, and thus hold A in position. Passing through B at its center and extending upward into A is a larger metallic point I, the upper end of which rests on the spiral wire spring Ic. This point punctures the paper, and constitutes the center around which the ellipsis is described. The,

J. B. ATWATER.

Witnesses:

GEORGE RICE, CHARLES ALEXANDER. 

